1. Field of the Invention.
This invention relates to a drain manifold for use with air data sensors for aircraft.
2. Description of Prior Art
Most existing aircraft require an extensive network of pneumatic lines connecting the pitot and static pressure signals to the tranducers and indicators located in the aircraft. On a large aircraft, this can result in several hundred feet of tubes or line. The problem is aggravated by the fact that the static pressure signals from the right and left hand sides of the aircraft are generally combined in a manifold before the line is directed to the pressure measuring and/or display locations.
U.S. Pat. No. 3,482,445 to DeLeo et al. discloses a strut mounted dual static tube having sensing ports designed for connection with pneumatic lines to remote instruments. Devices of this type require long lengths of pneumatic line. In addition, U.S. Pat. No. 3,482,445 does not utilize drainage valves which permit the lines to be drained regardless spatial orientation, which is, a desirable feature.
A water trap for a pitot-static system which comprises a separate housing is disclosed in U.S. Pat. No. 3,926,594 to Seib et al. The Seib device is designed for connection to remote instruments using substantial lengths of pneumatic line. The device can not be drained in spatial orientations 180 degrees apart and does not utilize drain outlets which permit drainage of a manifold or water trap.
A variety of gas-liquid separators have been previously used as well. For example, U.S. Pat. No. 3,668,822 to Mannion et al. shows a flow resistance equalizer for a liquid circulation system which includes a vent plug that can be released periodically to open the vent and release any air collected in an air chamber. Air collects in the chamber as the air is released from the flow of liquid due to a decrease in the velocity of the flow. Similarly, U.S. Pat. No. 3,867,115 to Heintzelman shows a gas-liquid separator comprising a vertical housing having a gas inlet and a gas outlet in an upper portion and a drain in a bottom portion thereof. Entrapped liquid is separated from the gas due to a decrease in velocity which occurs within the vertical housing. The Heintzelman device also provides for a resilient wipe which engages the interior surface of the vertical housing to prevent the flow of liquids and particulate impurities to reach the gas outlet of the separator.
Other gas-liquid separators of this type have been disclosed in U.S. Pat. Nos. 3,345,807 to Von Felden; 3,261,146 to Malec; 2,970,669 to Bergson; and 2,513,556 to Furczyk. Each of these patents discloses a housing equipped with a baffled or helical passageway in which entrapped liquids become separated from the inlet gas or air. These devices also provide means for removing the collected liquid from the housing through the use of some type of drain. However, the drainage methods used in these devices are dependent upon a single predetermined spatial orientation for effective drainage. This spatial orientation dependency means that different parts are required for installation on left and right sides of the aircraft.
U.S. Pat. No. 4,135,542 to Chisholm shows a drain device for compressed air lines having two outlet pipes mounted on opposite sides of the collection chamber, theoretically permitting the device to be drained when mounted right side up or inverted. However, the Chisholm device is designed to be used in association with compressed air lines rather than as a drain manifold for an air data sensor having multiple output lines. Chisholm does not disclose manifold-type connections which would permit the device to be directly mounted to a sensor of an air data sensor.
In the ideal case with air vehicle mounted sensors, all pneumatic lines would be completely eliminated, and even pneumatic averaging of signals from sensors on the right and left sides of the aircraft can be accomplished by electrical averaging. The present drain manifold can: (a) be a part of the pitot-static tube, the pitot tube, or a separate static probe, or (b) be placed in close proximity to such sensing probes, or (c) serve as mounting adapter for a pressure transducer assembly, or (d) be installed integrally with a pressure transducer assembly.